JP4242428B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a control device that suppresses fluctuations in the generated voltage of a generator that receives power from an internal combustion engine mounted on an automobile.

  Generally, a generator is attached to an internal combustion engine of an automobile to supplement electric power consumed by the vehicle. The generator is configured to generate power by transmitting power through a belt from a pulley attached to a crankshaft of the internal combustion engine.

  The conventional generator voltage control device changes the generator power generation voltage between engine strokes in order to suppress fluctuations in engine rotation during idle rotation. In the section where the voltage is increased and the engine speed is decreasing, the target power generation voltage is decreased. As a result, the generated voltage changes between engine strokes. (For example, see Patent Document 1).

JP 2004-137773 A

  FIG. 10 is a diagram showing a configuration of a power generation system similar to that of Patent Document 1. A generator 102 includes a coil 201 attached to the generator, and a field coil 202 that generates a magnetic flux interlinking with the coil 201. And a rectifier diode 203 for rectifying the generated voltage, and the vehicle battery 204 is charged by the output of the rectifier diode. Reference numeral 109 denotes field current amount adjusting means for adjusting the amount of current flowing through the field coil 202.

  FIG. 11 is a chart showing changes in engine speed and generated voltage during idling, and shows an example in which the target engine speed during idling of a four-cylinder engine is controlled to 750 rpm. Indicates the change in engine speed during one engine cycle. The top of the low rotational speed (time t1, t2, t3, t4) is the compression top dead center (hereinafter referred to as TDC) of each cylinder. In TDC, it is between the engine ignition strokes (180 ° CA for 4 cylinders). Since this load becomes maximum, as shown in FIG. 11A, the rotation speed becomes minimum.

  Further, in the vicinity of the central portion between the TDC and the next TDC, the load applied between the ignition strokes of the engine is minimized, so that the rotational speed is maximized as shown in FIG. In the case of a four-cylinder engine, the engine speed change described above is repeated four times in one engine cycle (720 ° CA). As described above, this chart is for a target engine speed of 750 rpm. In the case of a four-cylinder engine, the average engine speed between 180 ° CA is feedback controlled to the target engine speed. Since the engine load varies depending on the position, the rotational speed varies depending on the angular position. FIG. 11B shows a change in the generated voltage at this time, and shows an example in which the target generated voltage is set to 14.5V. The generated voltage changes in synchronization with the change in the engine speed, and the reason will be described with reference to FIG.

  FIG. 12 is a graph showing the relationship between the generator rotational speed and the field current when the power generation voltage of the generator is a predetermined voltage. The horizontal axis represents the generator rotational speed and the vertical axis represents the field current. . Since the engine and the generator are connected via a belt and the rotational speed ratio is 1.83 times, the engine rotational speed is about 600 rpm when the rotational speed of the generator is 1100 rpm. As can be seen from the graph, when the power generation voltage of the generator is constant, it is necessary to flow more field current as the rotation speed of the generator is lower, and the amount of current change particularly in the low rotation range becomes larger.

  In FIG. 11 (a), the rotational speed of the engine fluctuates between about 700 rpm and 800 rpm. At this time, the rotational speed of the generator varies between about 1280 rpm and 1460 rpm. In the feedback control of the generated voltage, the fluctuation of the voltage is detected and the field current is changed. However, because of this response delay, the generated voltage is not constant and the engine speed is changed as shown in FIG. It shows a change synchronized with the speed.

  Also, in order to reduce the fuel consumption of the vehicle, the idling engine speed tends to be set lower, and when a specific condition is satisfied in the idling condition, control is performed to reduce the engine speed especially. Is done. FIG. 13 shows a chart when the idling rotation speed is further reduced and the target rotation speed is 600 rpm with respect to FIG. 11, (a) shows the change in engine rotation speed, and (b) shows the generated voltage. It shows a change. As in FIG. 11, the engine speed in FIG. 13 (a) varies between the ignition strokes (180 ° CA), but the fluctuations in the engine speed during the ignition stroke tend to increase as the idle speed decreases. . Further, the generated voltage in FIG. 13B also fluctuates in synchronization with the change in engine speed, and the voltage fluctuation range increases as the engine speed decreases. As can be seen from the characteristics of the generator rotational speed and the field current amount shown in FIG. 12, the larger the generator rotational speed difference, the larger the field current difference at the same power generation voltage. The difference is more remarkable when the rotational speed is lower. It is. Therefore, the fluctuation of the generated voltage is further increased.

  A conventional control device for an internal combustion engine is configured as described above, and the power generation voltage of the generator is changed between the strokes of the engine, so that the power supply voltage of the automobile changes between the strokes. Further, even when the idling rotation speed is reduced, there is a problem that the change in the generated voltage becomes large although there is a merit that the fuel consumption can be reduced by the low rotation. When a voltage change occurs, there is a problem that a flickering of a headlight or an instrument panel lamp occurs, or a phenomenon that a voltage fluctuation causes a large noise to be given to an electric device.

  The present invention has been made in order to cope with the above-described problems, and is an internal combustion engine that can suppress fluctuations in the generated voltage, prevent the occurrence of lamp flickering, and reduce the noise applied to the electrical equipment. An object of the present invention is to provide an engine control device.

An internal combustion engine control apparatus according to the present invention includes an internal combustion engine that is mounted on a vehicle and supplies power to the vehicle, a generator that receives power from the internal combustion engine, and a rotation angle of a crankshaft of the internal combustion engine. Crankshaft rotation angle detecting means for detecting the crankshaft, crankshaft reference position determining means for detecting the reference position of the crankshaft from the output information of the crankshaft rotation angle detecting means, and the power generation according to the driving state of the vehicle a target voltage setting means for setting a target voltage of the machine, corresponding to the generated voltage set by the power generation voltage setting means and a field current adjustment means for adjusting the field current of the generator, is the detected Based on the crankshaft reference position and the crankshaft rotation angle , over the predetermined crank angle width across the compression top dead center during the ignition stroke from the compression top dead center to the next compression top dead center of the internal combustion engine. Generator Increasing the current by reducing the field current of the generator over a predetermined crank angle width sandwiching the central portion between the compression top dead center, of the generator varies in response to the ignition stroke This suppresses fluctuations in the generated voltage .

  The control apparatus for an internal combustion engine according to the present invention is configured as described above, and can reduce fluctuations in the power generation voltage of the generator depending on the stroke of the engine. A remarkable effect can be obtained in a state where the idling speed is low. As a result, flickering of headlights and instrument panel lamps can be improved, and noise generated by voltage fluctuations can be reduced.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a system configuration of a control device for an internal combustion engine according to the first embodiment. As shown in this figure, a generator 102 is connected to the engine 101 via its crank pulley and belt. The engine 101 is provided with a crankshaft rotation angle detection means 103, and outputs an output signal corresponding to the rotation angle of the crankshaft. The crankshaft rotation angle detecting means 103 is provided with a crank reference position detecting means 104 for detecting the output and detecting the reference position of the crankshaft from the output signal.

  Reference numeral 107 denotes an engine rotation speed calculation means for calculating the engine rotation speed from the crankshaft rotation angle detection means 103 and the crank reference position detection means 104. An output signal corresponding to the rotation angle is transmitted to the generator 102 to detect the rotation angle of the generator 102, and rotation angle information detected by the generator rotation angle detection means 105. Generator speed calculating means 106 for calculating the rotational speed of the generator 102 from the generator.

On the other hand, target voltage setting means 108 for setting the power generation voltage of the generator 102 according to the driving state of the vehicle and environmental conditions is provided, and the generator 102 is set in accordance with the power generation voltage set by the target voltage setting means 108. Field current control means 109 for adjusting the amount of field current is provided.
FIG. 2 is a diagram showing a detailed configuration of the voltage control device of the generator 102 shown in FIG. 10 that are the same as or correspond to those in FIG. A difference from FIG. 10 is that a generator rotation angle output means 601 for generating an output signal corresponding to the rotation angle of the generator 102 is provided, and this output signal is detected by the generator rotation angle detection means 105 shown in FIG. The rotation angle of the machine 102 is detected.

  Next, the operation of the first embodiment will be described using the chart of FIG. FIG. 3A is a chart showing changes in the engine speed, and the target engine speed is set to 600 rpm as in FIG. (B) is engine crank angle information detected and calculated by the crankshaft rotation angle detection means 103 and the crank reference position detection means 104, and represents the rotation angle between TDCs with TDC as 0 ° CA.

(C) is a field current control duty for driving the field current control means 109. For the field current control duty calculated from the target power generation voltage and the engine speed, the final field is calculated from the previously calculated field current control duty and the correction coefficient by calculating the correction coefficient according to the engine crank angle. It is the result of calculating the magnetic current control duty. As can be seen from FIGS. 3 (a), (b), and (c), the field current control duty increases the control duty in the vicinity of TDC (near engine crank angle 0 ° CA), and the center of TDC and the next TDC. Correction is performed so as to reduce the control duty in the vicinity.
Further, the field current control duty is corrected early according to the operating state in consideration of the response to the field current.

  (D) shows the change of the field current when the field current control duty corrected in (c) is used. Conventionally, the field current tended to decrease in a section where the engine rotation speed during one engine cycle is low, but in the first embodiment, the field current needs to be increased or decreased from the crank angle position of the engine. Since the field current control duty is changed in advance, the field current can be controlled without being influenced by the response delay of the field current. (E) shows a change in the generated voltage, and as a result of the above, shows that the amplitude of the generated voltage can be controlled to be small.

  Next, a field duty setting method according to the first embodiment will be described with reference to the flowchart of FIG. In step 401 of FIG. 4, the target power generation voltage is calculated and determined from the engine water temperature condition, the vehicle operating condition, and the like. Next, at step 402, the engine rotation speed calculation means 107 calculates the engine rotation speed. Step 403 is a step of calculating the field current control duty. The field current control duty (Df) is calculated and determined from the target generated voltage calculated in step 401 and the engine speed calculated in step 402.

  In step 404, it is confirmed whether or not a low idling condition that requires correcting the field current control duty is satisfied. The low idling condition is for judging that the engine operates stably even when the idling speed is lowered. The engine water temperature is equal to or higher than the predetermined water temperature, and the battery charge amount is equal to or higher than the predetermined value. It is determined that there is no failure and a low idling is determined. If No, the process proceeds to step 408, the field current control duty calculated in step 403 is set, and the field current control means 109 is driven. In this case, the field current control means 109 is driven with a constant field current control duty regardless of the crank angle position of the engine.

If yes in step 404, the process proceeds to step 405. In step 405, the engine crank angle is calculated. Based on the outputs of the crankshaft rotation angle detecting means 103 and the crank reference position detecting means 104, the crank angle between the TDCs of the engine is calculated.
In step 406, a field current control duty correction coefficient is calculated. In order to change the field current amount according to the engine crank angle position, a field current control duty correction coefficient corresponding to the engine crank angle is calculated.

  Next, a method for setting the field current control duty correction coefficient will be described with reference to FIG. 5, and steps after step 407 will be described later. FIG. 5A is a map for obtaining the correction coefficient K1 according to the crank angle, the horizontal axis is the crank angle before top dead center (BTDC), and the vertical axis is the correction coefficient K1. In this map, the correction coefficient K1 is determined using the crank angle calculated in step 405 of FIG. The correction coefficient K1 is set such that the closer the engine crank angle is to TDC, the larger the coefficient, and the smaller the coefficient near the center of the TDC and the next TDC.

FIG. 5B is a map for obtaining the correction coefficient K2 based on the engine rotation speed. The horizontal axis represents the engine rotation speed, and the vertical axis represents the correction coefficient K2. In this map, the correction coefficient K2 is determined using the engine speed calculated in step 402 of FIG. The correction coefficient K2 is set so that the coefficient increases as the engine speed decreases. Returning to FIG. 4, step 407 performs field current control duty correction calculation. The field current control duty (Df) calculated in step 403 and the field current control duty correction coefficient (K 1, K 2) calculated in step 406. ) To calculate the field current control duty (Df2) after the correction calculation.
That is, Df2 = Df × K1 × K2.
Thereafter, in step 408, the field current control duty is set, and the field current control means 109 is driven.

  Since the first embodiment is configured as described above and the field current control duty is set in consideration of the field current and the response delay of power generation according to the crank angle of the engine, the engine speed between TDCs is low. In the region where the generated voltage decreases, the field current is increased to prevent the generated voltage from dropping, and in the region where the engine speed between TDCs is high and the generated voltage is increased, the field current is decreased to generate the generated voltage. Will be prevented. As a result, the fluctuation of the generated voltage with respect to the target generated voltage can be reduced, and the generated voltage control accuracy is improved. In addition, flickering of lamps due to fluctuations in generated voltage and generation of noise can be suppressed.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. The system configuration of the control device is slightly different from that shown in FIG. 1, but the difference will be described later and is not shown.
Next, the operation of the second embodiment will be described using the chart shown in FIG.

  FIG. 6A is a chart showing changes in the rotational speed of the engine, and the target engine speed is set to 600 rpm as in the first embodiment. (B) is a chart showing changes in the engine reference position signal. The engine reference position signal outputs a falling edge when the crank angle of the engine reaches the TDC of each cylinder, and a rising signal when the crank angle of the engine reaches BTDC 90 ° CA, which is intermediate between the TDC and the next TDC. It is designed to output.

  (C) is a chart showing changes in generator rotation speed. Since the generator is connected to the crankshaft of the engine via a belt, the engine rotational speed and the generator rotational speed are in a proportional relationship. In this embodiment, the generator rotational speed is set to about 1.83 times the engine rotational speed. Therefore, the engine rotation angle and the engine rotation speed can be obtained from the generator rotation angle and the generator rotation speed. (D) is engine crank angle information, which represents the rotation angle between TDCs with TDC set to 0 ° CA. In the first embodiment, this information is calculated by the crankshaft rotation angle detecting means 103 and the crank reference position detecting means 104. In the second embodiment, the engine crank reference position information shown in FIG. 6B and the information shown in FIG. The engine crank angle information is calculated from the generator rotation speed information. Specifically, the engine crank angle corresponding to the generator rotation angle is calculated using the engine crank angle obtained from the generator rotation angle. When the engine reference position falling signal is detected, the crank angle can be calculated as shown in (d) by resetting the engine crank angle to 0 ° CA. The field current control duty of (e), the field current of (f), and the generated voltage of (g) are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, a field duty setting method according to the second embodiment will be described with reference to the flowchart of FIG. In this flowchart, the same steps as those in FIG. 4 are denoted by the same step symbols as those in FIG.

  If yes in step 404, the rotation angle of the generator is calculated based on the output of the generator rotation angle detecting means 105 in step 701. Next, at step 702, the engine crank angle is calculated. In this step, the crank angle rotation angle of the engine is calculated by multiplying the generator rotation angle calculated in step 701 by a coefficient. Specifically, the engine crank rotation angle is obtained by multiplying the generator rotation angle by a factor of 1 / 1.83. Subsequently, the routine proceeds to step 406, where the field current control duty correction coefficient is calculated from the engine crank rotation angle calculated at step 702. The subsequent steps are the same as in FIG.

  FIG. 7B is a flowchart for performing an interrupt processing calculation of the engine reference position. This routine is set so that interrupt processing occurs at the TDC (falling edge) of the engine reference position signal shown in FIG. When the engine reference position signal is interrupted, the generator rotation angle is reset to 0 in step 703. In the next step 704, the engine crank angle is reset to 0 and the interruption process is terminated. When the interruption by TDC occurs in this way, in the next routine for setting the field duty, the generator rotation angle in step 701 and the engine crank rotation angle in step 702 start with coefficients from 0, and FIG. It is possible to calculate the engine crank rotation angle shown in FIG.

The second embodiment is configured as described above, and the field current control duty is set in consideration of the field current and power generation response delay according to the crank angle of the engine, so that the engine speed between TDCs is low. In the region where the generated voltage decreases, the field current is increased to prevent the generated voltage from dropping, and in the region where the engine speed between TDCs is high and the generated voltage is increased, the field current is decreased to generate the generated voltage. Will be prevented. As a result, fluctuations in the generated voltage with respect to the target generated voltage can be suppressed, and the generated voltage control accuracy is improved. In addition, flickering of lamps due to fluctuations in generated voltage and generation of noise can be suppressed.
Further, the crank angle of the engine is estimated and calculated based on the engine reference position information and the generator rotation angle information, and the configuration can be simplified as compared with the first embodiment.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to the drawings. The system configuration of the control device is slightly different from that shown in FIG. 1, but the difference will be described later and is not shown.
Next, the operation of the third embodiment will be described using the chart shown in FIG.

  FIG. 8A is a chart showing changes in the rotational speed of the engine, and the target engine speed is set to 600 rpm as in the first and second embodiments. FIG. 8B is a chart showing changes in the rotational speed of the generator. (C) is a chart showing changes in the engine crank angle. In the third embodiment, the engine crank angle is estimated and calculated based on the generator rotational speed information. As described above, since the engine rotation angle and the generator rotation angle are in a proportional relationship, the engine crank rotation angle can be estimated and calculated from the generator rotation angle.

  Further, the engine rotation speed can be calculated from the generator rotation speed, and the TDC position can be estimated from the change in the engine rotation speed during one stroke. Thus, the engine crank angle shown in FIG. 8C can be estimated from the generator rotational speed. Since the field current control duty of FIG. 8D, the field current of FIG. 8E, and the generated voltage of FIG. 8F are the same as those in the first and second embodiments, description thereof is omitted.

  Next, a field duty setting method according to the third embodiment will be described with reference to the flowchart of FIG. In this flowchart, the same steps as those in FIG. 4 are denoted by the same step symbols as those in FIG.

  In step 901, the generator rotation speed is calculated by the generator rotation speed calculation means 106. In step 902, the engine speed is calculated. This can be obtained by multiplying the generator rotational speed calculated in step 901 by a factor (1 / 1.83). Next, calculation in step 403 and confirmation in step 404 are performed. If yes in step 404, the process proceeds to step 903. In step 903, the generator rotation angle is calculated, and the generator rotation angle (ΔθGn) after the previous processing is calculated by the generator rotation angle detection means 105 is calculated.

Step 904 is a step of estimating and calculating the engine crank angle, and the processing content is shown in the flowchart of FIG. In step 905, the engine rotation angle (ΔθEn) is calculated from the generator rotation angle (ΔθGn) calculated in step 903. Since the generator rotational speed and the engine rotational speed have a coefficient multiplication relationship, the engine rotational angle (ΔθEn) after the previous processing is calculated as follows.
ΔθEn = ΔθGn ÷ 1.83

Step 906 is a step of estimating the engine crank angle. The engine crank angle (θEn) is updated from the engine rotation angle (ΔθEn) calculated and updated in step 905 to estimate the angle. The engine crank angle (θEn) is calculated as follows.
θEn = θEn-1 + ΔθEn

  Step 907 is a step for estimating the engine reference position. As described above, the rotational speed of the engine is the lowest near the TDC of the engine and the highest near the middle between the TDC and the next TDC. Since the engine rotation speed and the generator rotation speed are proportional, the rotation speed is the lowest in the range of the rotation angle corresponding to the engine crank angle 180 ° CA calculated in step 904 (the rotation angle between the TDC and the next TDC). The part is near TDC. Therefore, the angular position at which the rotation speed between TDCs is the lowest is estimated as the reference position (TDC).

  Step 908 is a step for estimating whether or not the current position is the reference position. If yes, the crank angle estimated in step 906 is reset to 0 ° CA and the process is terminated. If the calculation of the engine crank angle is completed in step 904, the process proceeds to step 406. Since step 406 and subsequent steps are the same as those in the first and second embodiments, description thereof will be omitted.

The third embodiment is configured as described above, and the field current control duty considering the field current and power generation response delay is set according to the crank angle of the engine, so the engine speed between TDCs is low. In the region where the generated voltage decreases, the field current is increased to prevent the generated voltage from dropping, and in the region where the engine speed between TDCs is high and the generated voltage is increased, the field current is decreased to generate the generated voltage. Will be prevented. As a result, the fluctuation of the generated voltage with respect to the target generated voltage can be reduced, and the generated voltage control accuracy is improved. In addition, flickering of lamps due to fluctuations in generated voltage and generation of noise can be suppressed.
Furthermore, since the engine crank angle is estimated and calculated based on the generator rotation speed information and the generator rotation angle information, the crank angle position can be obtained without the engine rotation information. Compared to the second embodiment, the configuration can be greatly simplified.

  In each of the above-described embodiments, the average engine speed is calculated, and when the average engine speed is equal to or lower than the predetermined engine speed, the field current amount of the generator is adjusted according to the crank angle. The same effect as each embodiment can be expected.

1 is a block diagram showing a system configuration of a control device for an internal combustion engine according to Embodiment 1 of the present invention. FIG. It is a figure which shows the detailed structure of the voltage control apparatus of the generator shown in FIG. 2 is a chart showing a method for controlling a generated voltage during one engine cycle in the first embodiment. 3 is a flowchart for explaining a field duty setting method according to the first embodiment; 6 is a map for explaining a correction coefficient setting method in the first embodiment. 5 is a chart showing a method for controlling a generated voltage during one engine cycle in a second embodiment. 10 is a flowchart illustrating a field duty setting method and an engine reference position interrupt calculation processing method according to the second embodiment. 10 is a chart showing a method for controlling a generated voltage during one engine cycle in a third embodiment. 10 is a flowchart illustrating a field duty setting method and an engine crank angle estimation method according to a third embodiment. It is a figure which shows the system configuration | structure of the control apparatus of the conventional internal combustion engine. It is a chart which shows the engine speed and the change of a generated voltage between the conventional engine 1 cycles. It is a graph which shows the characteristic of the rotational speed and field current amount of a general generator. It is a chart which shows the engine speed and the change of a generated voltage between the conventional engine 1 cycles.

Explanation of symbols

101 engine, 102 generator, 103 crankshaft rotation angle detection means,
104 crank reference position detection means, 105 generator rotation angle detection means,
106 generator rotation speed calculation means, 107 engine rotation speed calculation means,
108 target voltage setting means, 109 field current control means.

Claims (4)

An internal combustion engine mounted on a vehicle for supplying power to the vehicle, a generator for receiving power from the internal combustion engine and generating power, crankshaft rotation angle detection means for detecting the rotation angle of the crankshaft of the internal combustion engine, Crankshaft reference position setting means for detecting the reference position of the crankshaft from output information of the crankshaft rotation angle detecting means, and target voltage setting means for setting the target voltage of the generator according to the driving state of the vehicle And a field current adjusting means for adjusting the field current of the generator corresponding to the generated voltage set by the generated voltage setting means, and the detected crankshaft reference position and crankshaft rotation angle Based on the compression top dead center of the internal combustion engine to the next compression top dead center, the field current of the generator is increased over a predetermined crank angle width across the compression top dead center during the ignition stroke. Center between top dead centers By reducing the field current of the generator over a predetermined crank angle width sandwiching the internal combustion engine, characterized in that to suppress the fluctuation of the power generation voltage of the generator varies in response to the ignition stroke Control device. An internal combustion engine mounted on a vehicle for supplying power to the vehicle, a generator for receiving power from the internal combustion engine and generating power, crankshaft rotation angle detection means for detecting the rotation angle of the crankshaft of the internal combustion engine, Crankshaft reference position determining means for detecting the reference position of the crankshaft from output information of the crankshaft rotation angle detecting means, target voltage setting means for setting the target voltage of the generator in accordance with the driving state of the vehicle, A field current adjusting means for adjusting the field current of the generator corresponding to the generated voltage set by the generated voltage setting means; and a generator rotation angle detecting means for detecting the rotation angle of the generator. calculates a crank angle of the internal combustion engine and a rotational angle of the crank reference position and the generator of the internal combustion engine, based on the calculated crank angle, following the compression top dead center from the compression top dead center of the internal combustion engine The field current of the generator is increased over a predetermined crank angle width that sandwiches the compression top dead center between the ignition strokes until the above crank angle width across the predetermined crank angle width that sandwiches the central portion between the compression top dead centers. A control device for an internal combustion engine, characterized in that fluctuations in the power generation voltage of the generator, which fluctuate in accordance with the ignition stroke, are suppressed by reducing the field current of the generator . An internal combustion engine that is mounted on a vehicle and supplies power to the vehicle, a generator that generates power by receiving power from the internal combustion engine, and a target voltage that sets a target voltage of the generator according to the operating state of the vehicle Setting means, field current adjusting means for adjusting the field current of the generator corresponding to the generated voltage set by the generated voltage setting means, and generator rotation angle detection for detecting the rotation angle of the generator Means, a generator rotation speed detection means for detecting the rotation speed of the generator, a rotation angle detected by the generator rotation angle detection means, and a crank angle of the internal combustion engine from the rotation speed detected by the generator rotation speed detection means. comprising an internal combustion engine crank angle estimating means that estimates, based on the crank angle position estimated by the internal combustion engine crank angle estimating means, ignition line from the compression top dead center of the internal combustion engine up to the next compression top dead center The field current of the generator is increased over a predetermined crank angle width sandwiching the compression top dead center therebetween, and the generator field is expanded over a predetermined crank angle width sandwiching the central portion between the compression top dead centers. A control apparatus for an internal combustion engine, characterized by suppressing fluctuations in the generated voltage of the generator, which fluctuates corresponding to the ignition stroke, by reducing the magnetic current .   4. The control apparatus for an internal combustion engine according to claim 1, wherein an average rotational speed of the internal combustion engine is calculated, and the average rotational speed is equal to or less than a predetermined value according to a crank angle. A control apparatus for an internal combustion engine, characterized in that a field current of the generator is adjusted.

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